Method and apparatus for copying



1954 R. A. FOTLAND ETAL METHOD AND APPARATUS FOR COPYING 2 Sheets-Sheet 1 Filed March 16, 1962 FIG. I.

FIG. 2.

'IIIlIIIIIIIIIII/Il nlllllllllllll IIHIHIHHllu INVENTORS Richard A. Foflond Virgil E. Sfroughan Kim )M ATTORNEY 18, 1954 R. A. FOTLAND ETAL 3,

METHOD AND APPARATUS FOR COPYING Filed March 16, 1962 2 SheetsSheet 2 FIG. 5.

Red Fi Hen Ye|low Filter no. 6. FIG. 7.

INVENTORS Richard A. Fofland Virgil E. Sfroughan ATTORNEY United States Patent 3,121,375 IWETHGDAND APPARATUS FUR COPYING Richard A. Fotlanii, Maple Heights, and Virgil E.

Stranghan, Euclid, Ohio, assignors'to Horizons Incorporated, a corporation of New Jersey Filed Mar. 16, 1%2, Ser. No. 180,240 3 Claims. (Ci. 951.7)

imply a low cost, maintenance-free system.

There are already known a variety of useful modes of reproducing ofiice copies of documents, including systems based on wet chemistry, e.g. silver halide systems utilizing the diifusion transfer of silver from a negative to the copy paper to form a visible image; or diazo systems utilizing specially treated paper and involving development by means of ammonia fumes; or dye-gelatin transfer systems. In addition, there are also known dry systems based on infrared exposure onto a sensitized photocopy paper; dry systems based on magnetic inks; and dry systems based on electrostatic photography.

Each of the known systems is of particular utility in specific areas but each suffers from technical limitations and economic disadvantages which limits its applicability more generally.

A principal object of the present invention is to provide a copying system which is of general applicability and which suffers from relatively few disadvantages.

A further object is to provide a system capable of copying color as well as black and white.

These and other objects are achieved in the present invention which provides a method and apparatus in which, a plurality of photoconductive elements are utilized to control an electric field disposed closely adjacent to the medium'on which the copy is to be formed, said electric field in turn controlling the development of a visible image by controlling the application of suitable developer material to the copy carrying medium, such as paper, or other suitable material.

a In its most rudimentary form, the apparatus comprises essentially the following components:

(1) Means for exposing the document to be copied to illumination;

(2) An optical system for projecting the image formed by said exposure to illumination onto a photoconductiveresistive bridge controller, which establishes anelectrical field adjacent to the medium on which copy is formed;

(3) Means for developing a readable copy including a developer manifold and distribution system; also located closely adjacent said electric field; and it may include means for moving both the original document and the copy through the apparatus at controlled and related speeds.

One preferred form of suchxapparatus is shown in the drawings in which:

FIGURE 1 is a schematic view of the apparatus;

FIGURE 2 is an enlarged view in profile on plane 22, of FIGURE 1;

FIGURE 3 is a still furtherenlar-ged view in section taken on plane 33, of FIGURE 2;

FIGURE 4 is a fragmentary view of the. photoconductor-resistive bridge controller shown in FIGURES 1-3;

FIGURE 5 is a schematic of a modified apparatus for forming colored images; and

:photoresist-etching technique.

3,121,375 Patented Feh. I8, I94

FIGURES 68 are diagrams of alternate development schemes.

As shown schematically in FIGURE 1, the apparatus comprises a housing 10 supported on a base 12 and provided with inlets 14 and 16 located in one side wall 18 of the housing, said inlets being preferably in the form of wide slits, and constituting means whereby the original document 0 and the material on which it is to be reproduced as a copy C are admitted into the housing. These materialsmay exist either as single sheets, or in the form of endless webs, or in any other convenient form. Anotherwall of the housing 10, which is preferably sidewall 20 opposite to sidewall 18, is provided with an outlet aperture 22 similar to inlet :14, said outlet constituting the means through which the original may be discharged from the housing and with a similar aperture 24 through which the copy may exit from the apparatus. Suitable means, known in the art and not shown in the several figures,

are provided for feeding the original document and copyreceiving medium into and through the machine at. any

desired relative speeds. lMeans provided to illuminate a portion of the document to be copied include a baffle 30, disposed parallel to and relatively close to the surface of the original document or other material to be copied, and a plurality'of light sources 3 4 and reflectors 35 or other means for directing a concentrated beam of illumination towards at slit 32 in baflie 30. By these means a narrow width across the original document is exposed to bright and intense illumination as the original moves past the exposure slit 32 in the baffle.

Means are provided to scan a narrow line or band of the original as it passes slit 32, and to transmit the image received to a control plate 40, shown in greater detail in FIGURES 2-4. The scanning means include one or more focussing lenses 36 and a mirror 38 positioned so as to direct the image of the material to be reproduced onto the surface of the control plate it). Lenses 36 may be supplemented by anyconvenient optical system whereby the image may be enlarged or reduced in size before being received on the surface of the control plate.

As best seen in FIGURES 2, 3 and 4, control plate 40 on which-the projected'image of a small area of the original is received, comprises a solid glass member 41, having a generally prismatic appearance and defined by a ilat base portion 44 from which two sides-46 and 48 extend upwardly and merge in an arched upper surface 5i comprising the upper surface of member 41. Deposited upon the outer surfaces of member 4 1 are a plurality of conducting electrodes 52. Conducting electrodes 52 are preferably in the form of stripes which pass over the arched top surface of the glass member 41 and which connect photoconduotive strip elements 54 disposed on opposite vertical sides of glass member 41. A plurality of photoconductive strips 54 are deposited on both sides of element 41 so that the upper end'of each photoconductor strip 54 is in contact with a conductive stripe 52, while all of the lower ends of the photoconductors 54 make electrical connection to one or the other of a pair of electrodes 56 each of which extends transversely along the lower portion of a side of glass block 4-1. Electrodes 56 are connected through leads 58 and 60, respectively to a source of potential 62.

The conducting electrodes may be formed on glass block'41 by any of several well known techniques such as by vapor deposition through a mask or by utilizing a The photoconductive strip 5'4, preferably formed of cadmium sulfide or cadmium sulfoselenide, may be deposited either by spraying a cadmium sulfide powder together with a suitable plastic binder through a mask or by vapor vacuum depositing cadmium sulfide through a mask and directly onto the surface of member 41. Other geometrical configurations may also be employed in forming the control element shown in FIGURE 4. For example, instead of being underneath the photoconductive strips 54, the electrode 56 may be deposited directly over the photoconductor 54 while the connecting stripe electrodes 52 may be extended under the photoconductive elements 54. In this modification the electrode 56 must be sufliciently thin so as to be semi-transparent. In this configuration the current passes between electrodes 52 and 56 in a transverse direction through the thin section of 54. This configuration would provide for higher current for the same resistivity photoconductor.

Means are also provided in the housing It to dispense a suitable developer to the copy medium, such means being generally indicated as 70 in FIGURES 1 and 3.

In operation, potentials are applied to the control plate as shown in FIGURE 3. A conducting developer manifold 70 is held at ground potential while equal and opposite potentials are applied to the electrodes 56. The developer manifold is filled with developer 72 which may be, for example, either a powder cloud comprised of minute solid particles or a liquid aerosol. In the dark, the potential of electrode 52 is equal to zero, since the bridge comprising photoconductors on either side of the glass plate is balanced. When light is incident upon the photoconductors 54 connected to the positive electrode 56, the resistivity of photoconductors 54 in the exposed areas decreases, thereby raising electrode 52 in potential. The electric field which is then present between electrode 52 and the developer manifold causes the developer particles in the manifold to be drawn down upon the paper, thereby forming a visible image on the paper. It is evident that this image will only be formed over those electrodes 52 connected to an adjacent photoconductor 54 which is exposed to illumination. If the developer powder is black, it can be seen that this technique results in the formation of a negative image, since where light is present the dark material is deposited upon the paper C. A direct positive image may be obtained by raising the potential of the developer manifold to the same potential to which the electrode stripes 52 are raised during the time light is incident upon 54. In this instance, the absence of light on photoconductors 54 reduces the potential of electrode 52 to zero and therefore a black image is developed in unexposed areas thereby yielding a positive image.

The apparatus shown in FIGURE 5 consists of essentially the same general components as those shown in FIGURE 1, with the following exceptions: In the embodiment shown, the original is now caused to travel in a path passing through the upper portion of the apparatus and the copy receiving member is caused to pass through the lower portion of the housing. As a result the optical system which is otherwise similar to that shown in FIG- URE 1 is oriented accordingly. Either arrangement may be used for monocolor or multicolor work. The really significant addition to the structure shown in FIGURE 1 is the provision of a plurality of developer manifolds, each associated with the use of a single color and each being controlled by illumination passing through a filter selected so that the developed image is that of a single color, red, blue and yellow being shown as one preferred system.

With the apparatus shown schematically in FIGURE 5, it is possible to develop copy in several colors by utilizing a plurality of sets of photoconductor strips each responsive to a single color, and by coupling each set with its own developer manifold, containing developer of a desired color.

The developers useful in the present apparatus are preferably either a suspension or a colloidal dispersion of carbon black or other finely divided pigment, suspended or dispersed in air or in an electrically insulating liquid such as carbon tetrachloride, or dimethyl or tetramethyl benzene. Developer compositions previously devised for use in xcrography and described in Carlson US.

Patents 2,221,776 and 2,297,691, and in Mayer US. Patent 2,890,174; Meyer and Straughan US. Patent 2,891,911; and Stranghan 2,899,339 and others of similar nature are suitable for the present invention.

FIGURES 6-8 show several other modes of applying developer in the practice of this invention. In FIGURE 6, a liquid developer such as those described in the above noted Mayer and/ or Straughan patents is formulated and a suitable amount is placed in a receptacle 9%. The developer is brought into physical contact with paper C by means of applicator rollers 92 and 94, roller 94 being located closely adjacent to the tip of control electrode 4t).

In FIGURES 7 and 8,'the developer manifold is formed from an insulating material 1%, terminating in a discharge tip 102 adjacent to the copy material and to the tip of control electrode 40. In FIGURE 7 there is an annular electrode 164 encircling the capillary containing developer tube while in the modification shown in FIGURE 8 there is a single electrode on that surface of developer supply member 1% which is opposite to the control electrode.

The following illustrates some of the modes in which the invention described above may be practiced and are to be considered illustrative rather than as exhaustive of the possible modes of exploiting the same.

Example 1 The photoconductor stripes 54 were applied to member 41 by hand in A3" wide stripes with the aid of artists brush. The photoconductor consisted of a mixture of (1018 in resin. The ratio of CdS to resin was about 10 to 1 which required thinning with toluene for application. The substrate was a square of opaque alumina ceramic. Electrodes were made by painting stripes of silver paint again with an artists brush. The resin was cured by heat before silver application.

A special holder was constructed to obscure the photoconductors on one side of the element from light while admitting it to the opposite side. Electrical connection could be made by screws passing through the insulating holder. Typical dark current through one of these photo-- conductor elements 4;" x at 600 volts was found to be .03 microampere. While illuminated with roonr light it increased to 1.5 microamperes and when illumi-' nated by a microscope light the current increased to 5.6 microamperes for a light to dark ratio of 186: 1.

A tray such as that shown in FIGURE 6 was filled with a charcoal-CCh developer of the type described in the aforesaid patents and which had been filtered through packing paper to remove large particles. The paper utilized was ordinary bond paper and was placed in contact with the upper roller of the two shown in FIGURE 6.

The power supplies were adjusted until no development would occur when the control plate 4% was pressed against the paper and while the photoconductors on both sides were covered. A good working potential was 300 volts. The feasibility of this system was first shown by merely touching the printing head to the paper with and without the light on. Black marks occurred when illuminated. Next, the printing head and electrode were clamped in close proximity and the paper slowly drawn between them with and without the light on. The results clearly showed the effect of light.

Example 2 The experiment in Example 1 was repeated except that higher resolution was achieved by clamping a U-shaped wire around the print-head in contact with the silver stripes. This provided line contact with the paper. Even here a fringing effect occurred with deposition of charcoal particles taking place on either side of the line of contact. In this experiment only one power supply was used. The developer roller was made negative and illuminated photoconductor electrode made positive. Best results were achieved at volts. In this arrangement, tailing out, of

the developed image was less pronounced than when two power sources were used. Still higher resolution resulted from butt-soldering fine wires to the U-shaped wires to provide point contact with traveling paper.

Example 3 Still further improvement was obtained by using only the U-shaped line-contacting wires. Again using only one power source as before, the negative lead was left unattached to anything and the roller electrode was either floating or grounded, the fringing efiect disappeared and printing occurred at the line of contact with paper. Shorting the roller electrode to the positive electrode immediately stopped development.

The system described is basically a line scan device, the operation of which is believed to be readily apparent from the preceding description.

The original is fed into the machine, preferably through inlet 14, at the same speed as the paper upon which an image is to be reproduced is fed into the machine through inlet 16. As the two move through the machine, the original passes slit 32 and as it is illuminated each incremental area across the original provides an optical image which is focused upon the photoconductors on sidewall 46. The conductors on the opposite sidewall 48 are maintained dark. The optical image controls the printing operation which occurs in a line across the copy paper. The resolution in a direction parallel to the direction of paper travel is determined by the scanning slit width and by the size of the developer distribution system. A high resolution in the other direction is obtained by utilizing a very large number of photoconductor bridge control elements.

Having now described our invention in accordance with the patent statutes, it is not our intention to be limited by said description except as required by the appended claims.

We claim:

1. An apparatus for generating hard copy from an original document comprising:

means to illuminate a document to be copied one portion at a time;

a manifold containing conductive particles of developer material disposed adjacent to the path of a copy receiving medium;

a control electrode comprising: a block of electrically insulating material, a plurality of photoconductive electrodes disposed in a generally parallel array on one side of said block, a second plurality of photoconductive elements arranged in a similar array on the opposite side of said block, and a plurality of electrically conductive elements connecting one each of said photoconductive elements with a corresponding element on the opposite face of said block;

a source of potential connected across said two arrays of photoconductive elements;

means to project an image of the illuminated portion of said document onto one of said arrays of photoconductive elements while maintaining the other array of photoconductive elements in the dark, whereby an electrical field is created between the surface of said block bearing said electrically conductive members and said conductive developer manifold, said field constituting the means to project developer particles onto a copy receiving medium disposed adjacent to said control electrode, which field causes said projected developer particles to be deposited on said copy receiving member in response to said field whereby a visible image corresponding to the illuminated portion of the original document is produced on the copy member.

2. The apparatus of claim 1 wherein the block has a generally arched cross section, the peak of which constitutes the portion of the body adjacent the copy-receiving medium and also adjacent the supply of projected developer.

3. A control electrode for use in a photoreproduction apparatus comprising a solid block of electrically insulating material; said block having two sidewalls which extend outwardly from a base generally parallel to one another for a first portion of their extent and which then turn toward one another and intersect in a straight line along a second portion of their extent; a plurality of stripes of photoconductive material deposited on each of said sidewalls; stripes of electrically conductive material deposited onthe portions of said block extending along both sides of said edge; planar electrodes located along the surface of said first portions, constituting means connecting said photoconductive stripes to a source of potential applied across the surface of said block.

References Cited in the file of this patent UNITED STATES PATENTS 2,556,550 Murray June 12, 1951 2,584,695 Good Feb. 5, 1952 2,817,277 Bogdonoif Dec. 24, 1957 2,892,391 Mayo et al. June 30, 1959 2,914,996 Whitham Dec. 1, 1959 2,937,943 Walkup May 24, 1960 3,008,826 Mott et al. Nov. 14, 1961 3,057,719 Byrne et al Oct. 6, 1962 

1. AN APPARATUS FOR GENERATING HARD COPY FROM AN ORIGINAL DOCUMENT COMPRISING: MEANS TO ILLUMINATE A DOCUMENT TO BE COPIED ONE PORTION AT A TIME; A MANIFOLD CONTAINING CONDUCTIVE PARTICLES OF DEVELOPER MATERIAL DISPOSED ADJACENT TO THE PATH OF A COPY RECEIVING MEDIUM; A CONTROL ELECTRODE COMPRISING: A BLOCK OF ELECTRICALLY INSULATING MATERIAL, A PLURALITY OF PHOTOCONDUCTIVE ELECTRODES DISPOSED IN A GENERALLY PARALLEL ARRAY ON ONE SIDE OF SAID BLOCK, A SECOND PLURALITY OF PHOTOCONDUCTIVE ELEMENTS ARRANGED IN A SIMILAR ARRAY ON THE OPPOSITE SIDE OF SAID BLOCK, AND A PLURALITY OF ELECTRICALLY CONDUCTIVE ELEMENTS CONNECTING ONE EACH OF SAID PHOTOCONDUCTIVE ELEMENTS WITH A CORRESPONDING ELEMENT ON THE OPPOSITE FACE OF SAID BLOCK; A SOURCE OF POTENTIAL CONNECTED ACROSS SAID TWO ARRAYS OF PHOTOCONDUCTIVE ELEMENTS; MEANS TO PROJECT AN IMAGE OF THE ILLUMINATED PORTION OF SAID DOCUMENT ONTO ONE OF SAID ARRAYS OF PHOTOCONDUCTIVE ELEMENTS WHILE MAINTAINING THE OTHER ARRAY OF PHOTOCONDUCTIVE ELEMENTS IN THE DARK, WHEREBY AN ELECTRICAL FIELD IS CREATED BETWEEN THE SURFACE OF SAID BLOCK BEARING SAID ELECTRICALLY CONDUCTIVE MEMBERS AND SAID CONDUCTIVE DEVELOPER MANIFOLD, SAID FIELD CONSTITUTING THE MEANS TO PROJECT DEVELOPER PARTICLES ONTO A COPY RECEIVING MEDIUM DISPOSED ADJACENT TO SAID CONTROL ELECTRODE, WHICH FIELD CAUSES SAID PROJECTED DEVELOPER PARTICLES TO BE DEPOSITED ON SAID COPY RECEIVING MEMBER IN RESPONSE TO SAID FIELD WHEREBY A VISIBLE IMAGE CORRESPONDING TO THE ILLUMINATED PORTION OF THE ORIGINAL DOCUMENT IS PRODUCED ON THE COPY MEMBER. 